1. Field of the Invention
This invention relates to aircraft autothrottle systems and more particularly to a clutch mechanism for enabling the rapid connection and disconnection of the automatic throttle control to and from the throttle control lever.
2. Description of the Related Art
Throttle control levers or quadrants are generally provided in aircraft for use by the pilot in manually controlling the engine power as well as attitude control mechanisms such as the aircraft flaps. In more sophisticated aircraft, such throttle control is integrated with the flight control system and under normal flight conditions controlled thereby. It is essential, however, that in the event of a malfunction or other emergency situation that the pilot be able to instantly and positively take over control of the throttle. In such takeover situations, the pilot must be able to fully take over the control of the aircraft from the flight control system and when so desired instantly restore such automatic control. In implementing such instant switchover of operation, it is essential that the manual control lever be coupled to the flight control system when the system is in automatic operation so that such lever assumes and maintains the proper setting for any future manual takeover.
Prior art autothrottle systems are described in U.S. Pat. No. 3,599,510 issued Aug. 17, 1971 to Scott and U.S. Pat. No. 4,651,954 issued Mar. 24, 1987 to Miller. Miller employs a D.C. stepping motor in controlling the throttle system which is coupled to the throttle actuator through a drum type friction clutch pack. In Scott, the clutch between the control lever and the automatic control system employs a clutch having friction shoes. Neither of these references suggests a clutch mechanism employing a combination of wedge and roller elements such as that of applicant's system which is of simple and reliable construction and which provides positive clutch engagement and disengagement in response to a switch actuated solenoid.